clutch: change in sematic of addClutch loss, handle the case when braking to standstill

addClutchLoss: only add clutch loss, if clutch has to be opened handle this already in the request
braking to standstill: problem is that angular speed becomes 0, thus the power is 0 and consequently the input torque at engine side is 0 -> no engine drag when braking to standstill
solution: don't use 'angular velocity at the end of simulation interval but use average angular velocity, so that the torque is not 0.